powerpc: Randomise PIEs
Randomise ELF_ET_DYN_BASE, which is used when loading position independent
executables.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/include/asm/elf.h b/arch/powerpc/include/asm/elf.h
index 968b37f..1a856b1 100644
--- a/arch/powerpc/include/asm/elf.h
+++ b/arch/powerpc/include/asm/elf.h
@@ -179,7 +179,8 @@
the loader. We need to make sure that it is out of the way of the program
that it will "exec", and that there is sufficient room for the brk. */
-#define ELF_ET_DYN_BASE (0x20000000)
+extern unsigned long randomize_et_dyn(unsigned long base);
+#define ELF_ET_DYN_BASE (randomize_et_dyn(0x20000000))
/*
* Our registers are always unsigned longs, whether we're a 32 bit
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 30b149c..eac0649 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1170,3 +1170,13 @@
return ret;
}
+
+unsigned long randomize_et_dyn(unsigned long base)
+{
+ unsigned long ret = PAGE_ALIGN(base + brk_rnd());
+
+ if (ret < base)
+ return base;
+
+ return ret;
+}